I remember I had a problem with this once. I tried editing the file, but then another error popped up, then another (either another package not found or another file didnt find the ASDF package, dont remeber.). I didnt chase it down too far though. You can try installing slime from the website, or from the repositories, or try another version of Emacs from your repositories if you have an option. I would be curious what the problem is if you actually fix it.

I assuming that when you said "the package cl-asdf is installed on the system", you meant that you installed it via something like apt-get (since you mentioned Debian). Did you also install CLISP on the system the same way?

If you did, it would seem ironic to me (but not your fault of course), because it looks as if CLISP cannot see asdf to require it (or whatever the equivalent of require is in CLISP). To test that CLISP cannot reach asdf, try launching a CLISP REPL yourself (without slime) and enter the first form slime is trying, namely

If you get the same error about there being no asdf, then you know CLISP cannot reach asdf, and that slime is not to blame in this particular case.

Here's where my expertise ends. I don't know CLISP. So if a kind CLISPer soul doesn't answer here, I recommend you go to the CLISP docs and find out how CLISP should be wired up to reach any asdf packages. Good luck.

OK, thanks for your helpful support. I'm quite sure now that the problem resides within the swank-loader implementation that is part of the slime version in Debian's package repository. My first try was to fix the problem with an extended initialization in .emacs: